论文部分内容阅读
自从发现高分子液晶以来,对聚合物熔体中转变的研究逐渐为人们所重视。近年来,巳在多种聚合物熔体中发现了转变。在刚性链聚合物中发现的转变大都具有液晶相转变的性质。最近我们在四氟乙烯-六氟丙烯共聚物(FEP共聚物)熔体中也发现了这种转变。我们在研究熔体温度对FEP共聚物结晶形态及结晶性质的影响时,曾发现在310～320℃附近,FEP共聚物熔融结晶的形态明显地依赖于熔体温度~([1])。当熔体温度保持在320℃以上时,冷却结晶得到球晶形态;而当熔体温度低于310℃时,冷却得到晶片无规堆积形态;从310～320℃温度区间冷却结晶则形成棒晶。这些结晶形态的变化很易用小角光散射H_v图象来识别。同时,差示扫描量热仪测得的降温结晶曲线也随着熔体温度变化,发生突变的温度范围也在310～320℃之间。由于结晶形态和结晶性质的变化,均可以在同一试样中重复出现,因此,这种变化显然与熔体结构在此温度范围内发生变化有关,而不是由
Since the discovery of polymer liquid crystal, the study of the transition in polymer melt has gradually attracted people’s attention. In recent years, the transition has been found in a variety of polymer melts. Most of the transitions found in rigid chain polymers have the property of liquid crystal phase transitions. Recently we have also found this transition in tetrafluoroethylene-hexafluoropropylene copolymer (FEP copolymer) melt. When we studied the effect of melt temperature on the crystalline morphology and crystallinity of FEP copolymer, it was found that the morphology of FEP copolymer melt crystallized at 310 ~ 320 ℃ obviously depends on the melt temperature ~ ([1]). When the melt temperature is maintained above 320 ° C, the crystal is cooled to obtain the spherulite morphology; while when the melt temperature is below 310 ° C, the wafer is randomly deposited to form a crystal; the crystal is cooled and crystallized from 310 to 320 ° C, . These crystalline morphological changes are easily identified by small angle light scattering H_v images. At the same time, the differential cooling calorimeter crystallization curve also changes with the melt temperature, the mutation temperature range is between 310 ~ 320 ℃. Due to changes in the crystalline morphology and crystalline nature of the sample can be repeated in the same appearance, so this change obviously with the melt structure changes in this temperature range, rather than by the